A known bumper reinforcement for a vehicle is disclosed in JP2006-151095A (hereinafter referred to as Reference 1). As illustrated in FIGS. 7A and 7B, a bumper reinforcement 91 includes a main body 92 formed by an extruded member extending in a width direction of the vehicle. Both end portions of the main body 92 in the width directions are curved toward a vehicle body and are diagonally cut. The bumper reinforcement 91 further includes a reinforcement member 93 having a groove portion. The reinforcement member 93 is attached from a front side of the vehicle to a cut surface of each of the end portions of the main body 92; thereby, an inclined surface conforming to a design of the vehicle may be obtained at the end portion of the main body 92 while the end portion is not excessively bent. In addition, bending strength of the main body 92 may deteriorate because a portion of the end portion of the main body 92 is diagonally cut. However, the reinforcement member 93 is attached to the end portion of the main body 92. Therefore, for example, in a case where the vehicle collides and an impact obliquely acts on the vehicle, the reinforcement 93 may secure a certain degree of resistance against energy of the impact caused by the collision.
Moreover, a known bumper reinforcement for a vehicle, disclosed in JP2000-334530A (hereinafter referred to as Reference 2) is integrally formed by pressing or another processing technique. The bumper reinforcement is designed so that a section width gradually decreases from end portions to an intermediate portion in a width direction of the vehicle in order to reduce an impact applied to an occupant of the vehicle due to a collision against a full-width portion of a front side of the vehicle. Thus, the bumper reinforcement designed as described above may absorb a large impact energy caused by the front collision while reducing the impact applied to the occupant.
According to the bumper reinforcement 91 described in Reference 1, the reinforcement member 93 having a predetermined bending strength is attached to the cut surface of the end portion of the main body 92 by welding or by a mechanical attaching technique. As a result, the number of components of the bumper reinforcement 91 and man-hours in a manufacturing process of the bumper reinforcement 91 increase and therefore result in cost increases.
According to Reference 2, the section width of the bumper reinforcement is smallest at the intermediate portion. Therefore, in a case where a concentrated load acts only on an intermediate portion of the vehicle in the width direction when the vehicle collides, the intermediate portion of the bumper reinforcement may easily fracture; therefore, the bumper reinforcement is deformed into a substantially V-shape.
A need thus exists for a bumper reinforcement and a bumper device for a vehicle, which are not susceptible to the drawback mentioned above.